Cooking Appliance Mounted in an Elevated Manner

ABSTRACT

A cooking appliance which is mounted in an elevated manner and which comprises at least one muffle which defines a cooking area, whereby said muffle comprises an opening in the base thereof and which is surrounded by a muffle frame, a base door which is displaced by means of a drive device and which is used to close the muffle opening, at least one switch panel which is used to displace the base door in a directional manner. Said cooking appliance also comprises a memory unit which is used to memorise at least one target position of the base door, wherein the base door can be displaced in an automatic manner to the stored target position after the switch panel is actuated, until at least one target position is reached.

The present invention relates to a high-fitted cooking appliance havingat least one muffle that delimits a cooking chamber and has on its baseside a muffle opening, a base door that is displaceable by means of adrive device for closing the muffle opening, and at least onedisplacement switch panel for displacing the base doordirection-dependently.

Known from, for example, U.S. Pat. No. 2,944,540, DE 102 28 140 A1, andDE 101 64 239 A1 are high-fitted cooking appliances in the case of whicha base door is displaceable by means of a drive motor, with the basedoor being displaceable in the desired direction when a displacementbutton has been actuated.

It is disadvantageous that such an operating manner is inconvenient forthe user, especially since the desired final position can frequently bereproduced only with difficulty if not corresponding to a restingposition on a work plate or to a final position specified in the design.

The object of the present invention is therefore to provide ahigh-fitted cooking appliance that is simpler to operate and flexible interms of adjusting and displacing its base door.

The present object is achieved by means of the cooking appliance havingthe features of claim 1 and of the method as claimed in claim 18.

A memory unit for storing at least one target position of the base dooris provided for that purpose. If a target position requiring to beattained has been stored, then the base door will keep movingautomatically once the displacement switch panel has been actuatedaccordingly until said (next) target position has been reached(automatic operation).

It will be advantageous if the at least one target position can bestored by actuating an actuating button, for example for 2 to 4 seconds,with the base door at the target position. An actuating or storingsignal, for example an optical and/or acoustic signal, is then favorablyfed out.

Since the at least one displacement button, which is not limited intype, shape, or arrangement, needs to be actuated only briefly duringautomatic operation, for increased operational safety it will beadvantageous for a jamming-protection device to have been activated whena target position has been stored.

To ensure that the—then possibly incorrect or unsafe targetposition(s)—will have been cleared following a relocation or astructural alteration, the memory unit includes volatile memory chips,for example RAMs such as DRAMs, SRAMs, MRAMs etc., for storing thetarget position. However, so that not every fluctuation in the a.c.power supply will clear the target positions (also called displacementpositions), a power-failure buffer is provided typically for bridgingfluctuations or outages in said supply lasting up to a few seconds.

For quiet operation the base door can advantageously be started upgently and braked gently, favorably by means of a speed or load ramp,once a target position has been stored.

The base door can in the absence of a stored target position for adisplacement direction preferably be displaced only by appropriatelyactuating at least one of the displacement switch panels continuously(manual operation). Said target position can be absent if, for example,either no target position has been stored for that displacementdirection—for example only a target position for an open position hasbeen stored, which in the closing direction can mean the absence of atarget position that can be moved to—or the single or last targetposition for that displacement direction has already been reached and nofurther target position is available for a further displacement in thesame displacement direction. Manual operation will also become active ifthe displacement switch panel is actuated for longer than a specificmaximum actuating time for automatic operation, in particular 0.4seconds. Manual operation will then take precedence over automaticoperation even in the presence of a target position that can be movedto.

For increased operational safety, in the absence of a stored targetposition for a displacement direction it is advantageous for the basedoor to be displaceable only by appropriately actuating two displacementswitch panels continuously and simultaneously, i.e. with both hands.

For convenient displacing it is advantageous for the displacement switchpanels to be attached to the front of a permanently installable housing.They can, though, also be attached to, for example, opposite sides ofthe permanently installable housing or at other locations.

For increased operational safety it is also advantageous if duringmanual operation—i.e. when the base door will move only when thedisplacement switch panel has been actuated—the base door will, althoughstarting by moving gently, stop abruptly, i.e. will halt, for examplethrough short-circuiting of the drive motor, as soon as the relevantdisplacement panel has been released.

A jamming-protection device will advantageously have been deactivatedduring manual operation and activated during automatic operation.

The base door can advantageously be displaced, during manual and/orautomatic operation, even when the main switch is off.

For moving more precisely to the target positions it is possible toinitialize travel measuring at the zero position, meaning in the definedclosed condition. It is also favorable for travel measuring of thedisplacement path to be carried out incrementally and also for travelmeasuring of the displacement path—and hence of the position—of the basedoor to be carried out by means of at least one sensor, in particular aHall sensor, located on a motor shaft of the drive device.

There are two displacement switch panels for that purpose so that thebase door can be displaced only when both displacement switch panelshave been actuated in the same direction for displacing the base door.That two-handed operation will prevent jamming of a free hand.

At least one displacement switch panel preferably includes a separatedisplacement button for each displacement direction, thus typically ineach case an opening switch “OPEN” and a closing switch “CLOSE”, forexample pushbuttons. Thus both “OPEN” switches must have been actuatedfor displacing the base door in an opening direction and both “CLOSE”switches must have been actuated for displacing the base door in aclosing direction.

The invention is described schematically in more detail below with theaid of the attached figures:

FIG. 1 is a perspective view of a high-fitted cooking appliance mountedon a wall and having a lowered base door;

FIG. 2 is a perspective view of the high-fitted cooking appliance havinga closed base door;

FIG. 3 is a perspective view of a housing of the high-fitted cookingappliance without the base door;

FIG. 4 is a schematic side view, in cross-section along the line I-Ishown in FIG. 1, of the high-fitted cooking appliance mounted on thewall and having a lowered base door;

FIG. 5 is a front view of a further embodiment variant of a high-fittedcooking appliance;

FIGS. 6 to 11 are graphs of displacement movements of a base door underdifferent boundary conditions;

FIGS. 12 and 13 are force-time profile graphs for a base door.

FIG. 1 shows a high-fitted cooking appliance having a housing 1. Therear of the housing 1 is mounted in the manner of a hanging cabinet on awall 2. Defined in the housing 1 is a cooking chamber 3 that can bechecked via a viewing window 4 provided at the front in the housing 1.It can be seen in FIG. 4 that the cooking chamber 3 is delimited by amuffle 5 provided with a thermally insulating casing (not shown) andthat the muffle 5 has a muffle opening 6 on its base. The muffle opening6 can be closed by means of a base door 7. The base door 7 is shownlowered in FIG. 1, resting with its underside on a work plate 8 of anitem of kitchen furniture. In order to close the cooking chamber 3 thebase door 7 must be moved into the position shown in FIG. 2, which istermed the “zero position”. For moving the base door 7 the high-fittedcooking appliance has a drive device 9, 10. The drive device 9, 10 has adrive motor 9, indicated in FIGS. 1, 2, and 4 by means of dashed lines,which is located between the muffle 5 and an exterior wall of thehousing 1. The drive motor 9 is located in the area of the rear of thehousing 1 and, as shown in FIG. 1 or 4, is operatively connected to apair of lifting elements 10 linked to the base door 7. According to theschematic side view shown in FIG. 4 each lifting element 10 is thereinembodied as an L-shaped support whose vertical limb extends from thedrive motor 9 on the housing side. For moving the base door 7 the drivemotor 9 can be actuated with the aid of an operating panel 12 and acontrol circuit 13, which panel is according to FIGS. 1 and 2 located atthe front on the base door 7. As shown in FIG. 4, the control circuit 13is located behind the operating panel 12 inside the base door 7. Thecontrol circuit 13, consisting here of a plurality of spatially andfunctionally separate printed-circuit boards that communicate via acommunication bus, constitutes a central control unit for operating theappliance and controls and/or regulates, for example, heating,displacing of the base door 3, implementing of user inputs,illuminating, jamming protection, clocking the heating elements 16, 17,18, 22, and much more.

It can be seen from FIG. 1 that a top side of the base door 7 has acooking area 15. Virtually the entire surface of the cooking area 15 isoccupied by heating elements 16, 17, 18, indicated in FIG. 1 bydot-and-dash lining. The heating elements 16, 17 are in FIG. 1 twodifferently sized cooking-hob heating elements spaced apart, while theheating element 18 is a panel heating element provided between andalmost enclosing the two cooking-hob heating elements 16, 17. For theuser, the cooking-hob heating elements 16, 17 define associated cookingzones or cooking troughs; together with the panel heating element 18,the cooking-hob heating elements 16, 17 define a bottom-heat zone. Thezones can be indicated by means of a suitable decorative design on thesurface. The heating elements 16, 17, 18 can each be controlled via thecontrol circuit 13.

In the exemplary embodiment shown the heating elements 16, 17, 18 areembodied as radiating heating elements covered by a glass ceramic plate19. The glass ceramic plate 19 has approximately the same dimensions asthe top side of the base door 7. The glass ceramic plate 19 isfurthermore fitted with mounting openings (not shown) through whichprotrude bases for fixing securing parts 20 for supports 21 for itemsbeing cooked, as also shown in FIG. 4. Instead of a glass ceramic plate19 it is also possible to employ other—preferablyfast-reacting—coverings, for example a thin metal plate.

The high-fitted cooking appliance can with the aid of an operating knobprovided in the operating panel 12 be switched to a cooking-hoboperating mode or bottom-heat operating mode, which are explained below.

The cooking-hob heating elements 16, 17 can in the cooking-hob operatingmode be controlled individually via the control circuit 13 by means ofcontrol elements 11 provided in the operating panel 12, while the panelheating element 18 remains in the non-operating state.

The cooking-hob operating mode can be used with the base door 7 lowered,as is shown in FIG. 1. However it can also be used within the scope ofan energy-saving function when the cooking chamber 3 is closed with thebase door 7 raised.

In the bottom-heat operating mode not only the cooking-hob heatingelements 16, 17 but also the panel heating element 18 are controlled bythe control device 13.

To achieve maximally even browning of items being cooked using thebottom-heat mode it is crucial for the cooking area 15 providing thebottom heat to distribute the heating output evenly across the surfaceof the cooking area 15, although the heating elements 16, 17, 18 havedifferent nominal outputs. The heating elements 16, 17, 18 are thereforepreferably not switched to continuous operation by the control circuit13; the power supply to the heating elements 16, 17, 18 is insteadclocked. The different nominal heat outputs of the heating elements 16,17, 18 are therein reduced individually in such a way that the heatingelements 16, 17, 18 will distribute the heating output evenly across thecooking area's surface.

FIG. 4 shows schematically the position of a fan 23, for example forproducing circulating air in the case of hot-air operation or forducting fresh air inward. Further provided attached to a top side of themuffle 5 is a top-heat heating element 22 that can be embodied as ofsingle-circuit or multiple-circuit design, for example having an innerand an outer circuit. There can also be further heating elements—notshown here for the sake of greater clarity—, such as a ring-shapedheating element, between the back wall of the housing 1 and the muffle.The various operating modes such as, for example, also top-heat,hot-air, or quick-heat mode can be set by means of the control circuit13 by appropriately switching or setting the heat output of the heatingelements 16, 17, 18, 22, possibly with activating of the fan 23. Theheat output can be set by means of suitable clocking. The cooking area15 can furthermore be embodied otherwise, for example with or without afrying zone, as a pure—single-circuit or multiple-circuit—warming zonewithout cooking troughs, and so forth. The housing 1 has a seal 24toward the base door 7.

The operating panel 12 is arranged chiefly on the front of the base door7. Other arrangements are alternatively also conceivable, for example onthe front of the housing 1, distributed over different partial panels,and/or in part on side surfaces of the cooking appliance. Furtherembodiments are possible. The control elements 11 are not limited intheir structural design and can include, for example, operating knobs,toggle switches, pushbuttons, and membrane keys that include displayelements 14, for example LED, LCD, and/or touchscreen displays.

FIG. 5 is a schematic front view, not to scale, of a high-fitted cookingappliance in which the base door 7 is open and resting on the work plate8. The closed condition is indicated by dashed lining.

In that embodiment variant there are two displacement switch panels 25on the front of the permanently attached housing 1. Each displacementswitch panel 25 includes two pushbuttons, namely a top CLOSE pushbutton25 a for a base door 7 moving upward in the closing direction and abottom OPEN pushbutton 25 b for a base door 7 moving downward in theopening direction. The base door 7 will without automatic operation (seebelow) move upward, if possible, only through continuouslysimultaneously pressing the CLOSE buttons 25 a on both displacementswitch panels 25; the base door 7 will also move downward, if possible,only through continuously simultaneously pressing the OPEN buttons 25 bon both displacement switch panels 25 (manual operation). Since the userwill be more attentive to operation during manual operation and,moreover, both hands are used in that case, jamming protection will thenonly be optional. Displacement switch panels 26 are in an alternativeembodiment variant attached to opposite outer sides of the housing 1along with corresponding CLOSE buttons 26 a and OPEN buttons 26 b, asindicated by dotted lining.

The control circuit 13 that is indicated by dot-and-dash lining andlocated inside the base door 7 behind the operating panel 12 switchesthe drive motor 9 in such a way that the base door 7 will start movinggently, i.e. not abruptly through simple turning on of the drive motor 9but by means of a defined ramp.

The control circuit 13 includes in that exemplary embodiment a memoryunit 27 for storing at least one target or displacement position P0, P1,P2, PZ of the base door 7, preferably with volatile memory chips, forexample DRAMs. After one of the buttons 25 a, 25 b or, as the case maybe, 26 a, 26 b on the displacement switch panels 25 or, as the case maybe, 26 has been actuated, if a target position P0, P1, P2, PZ has beenstored the base door can continue moving automatically in the directionset until the next target position has been reached or one of thebuttons 25 a, 25 b or, as the case may be, 26 a, 26 b has been actuatedagain (automatic operation). The bottommost target position PZcorresponds in that exemplary embodiment to the maximum opening, the(zero) position P0 corresponds to the closed condition, and P1 and P2are freely configurable intermediate positions. When the last targetposition for a direction has been reached, it will thereafter benecessary to proceed using manual operation if that is possible (meaningif the last end positions do not correspond to a maximum open conditionor to the closed final condition). Analogously, if no target positionhas been stored for a direction—which would be the case, for example,for an upward direction to the closed position if only PZ has beenstored but not P0, P1, P2—, a displacement in said direction will haveto take place using manual operation. Automatic operation will not bepossible if no target position has been stored, for example in the caseof a new installation or following a disconnection from the a.c. powersupply. Jamming protection will preferably have been activated if thebase door 7 is displaced using automatic operation.

Automatic and manual operation are not mutually exclusive: The base door7 will through continuously actuating the displacement switch panel(s)25, 26 also move using manual operation if a target position could bemoved to in said direction. It is therein possible to, for example,specify a maximum actuating time, for instance 0.4 seconds, for thedisplacement panels 25 or, as the case may be, 26, or for the associatedbuttons 25 a, 25 b or, as the case may be, 26 a, 26 b, for activatingautomatic operation.

A target position P0, P1, P2, PZ can be any position of the base door 7between and including the zero position P0 and the maximum open positionPZ. However the maximum stored open position PZ does not have to be theposition resting on the work plate 8. The target position P0, P1, P2, PZcan be stored with the base door 7 at the desired target position P0,P1, P2, PZ by, for example, actuating an actuating button 28 in theoperating panel 12 for several seconds (for example two secondscontinuously). For the sake of greater clarity existing optical and/oracoustic signaling devices that feed out relevant signals when a targetposition has been stored have not been drawn. The desired targetposition P0, P1, P2, PZ requiring to be set is moved to by, for example,—in this exemplary embodiment—operating the displacement switch panels25 or, as the case may be, 26 with both hands and performing a manualdisplacement up to said position.

Just one target position or, as shown in this exemplary embodiment, alsoa plurality of target positions P0, P1, P2, PZ can be capable of beingstored in the memory unit 27. In the case of a plurality of targetpositions P0, P1, P2, PZ, they can be moved to consecutively byactuating the corresponding displacement buttons 25 a, 25 b or, as thecase may be, 26 a, 26 b. A plurality of target positions P0, P1, P2, PZwill allow the high-fitted cooking appliance to be matched convenientlyto the different operating heights desired by several users. The targetposition(s) can advantageously be cleared and/or overwritten. Forexample just one target position can in one embodiment variant be storedin the open condition while the zero position P0 will be detectedautomatically and can be moved to automatically. The zero position P0must alternatively also be stored so that it can be moved toautomatically.

For an ergonomic use it is particularly advantageous for the or a targetposition P1, P2, PZ to open the base door 7 at least approximately 400mm to approximately 540 mm (meaning P1-P0, P2-P0, PZ-P0≧40 cm to 54 cm).The supports 21 for items being cooked will at that opening extent beeasy to insert into the securing parts 20. It is therein favorable forthe viewing window 4 to be mounted approximately at the user's eye levelor somewhat lower, for example by means of a template indicating thecooking appliance's dimensions.

Not drawn is a power-failure buffer for bridging power outages lastingapproximately 1 to 3 s, preferably up to 1.5 s.

The drive motor 9 shown in FIG. 1 has at least one sensor unit 31, 32located on a motor shaft 30, where applicable in front of or behind agear, for measuring a displacement path or, as the case may be, aposition and/or speed of the base door 7. The sensor unit can include,for example, one or more induction, Hall, optical, or OFW sensors, andso forth. For simple path and speed measuring two Hall (sub-)elements 31are here attached displaced through 180° to the motor shaft 30—thusplacing them mutually opposite—and a Hall sensing element 32 isstatically attached to that area of the motor shaft at a distance. Whena Hall element 31 then passes the sensing element 32 when the motorshaft 30 turns, a measuring or sensor signal will be produced that isvery approximately digital. Two signals will hence be fed out with (notnecessarily) two Hall elements 31 when the motor shaft 30 turns once.The speed vL of the base door 7 can be determined by evaluating the timeof said signals, for example their time difference, for instance by wayof comparison tables or through real-time conversion in the controlcircuit 13. A displacement path or, as the case may be, a position ofthe base door 7 can be determined by adding or, as the case may be,subtracting the measurement signals.

A speed-regulating means can implement the speed via, for example, aPWM-controlled power-semiconductor device.

For determining the zero point, travel measuring is automaticallyrealigned by initializing in the zero position P0 of the base door 7each time it is moved so that for example a faulty sensor-signal outputor, as the case may be, reception will not propagate.

The drive motor 9 can also be operated by actuating both displacementswitch panels 25 or 26 with the main switch 29 deactivated.

Instead of two separate switches per displacement panel 25, 26 a singleswitch per displacement panel is also possible, for example a toggleswitch that has a neutral position and switches only under pressure.Other forms are also possible. The nature and arrangement of the controlelements 28, 29 of the operating panel 12 are not limited, either.

The arrangement of the control circuit 13 and the way it is distributedis therein flexible and not limited, so it can also include a pluralityof boards, for example a display board, a control board, and a liftboard, that are spatially separated.

A 4-mm opening extent can be detected by means of end switches 33 whichon actuation deactivate jamming protection.

The high-fitted cooking appliance can be embodied also without a memoryunit 27, with automatic operation then not being possible. That can beexpedient for increased operating safety, for example as a safeguardagainst jamming.

FIG. 6 is a graph, not to scale, plotting the displacement speed vL ofthe base door 7 in mm/s against said door's position in mm from the zeroposition P0 for a displacement of the base door 7 from the closedcondition at P0=0 mm to PZ=maximum opening at, in this case, 530 mmduring a manual displacement operation (thus withoutautomatic-displacing means) as well as, indicated by the dotted arrow,stopping of the displacement movement between P0 and PZ. The curve runsin the direction of the arrow, meaning from right to left. The downwardarrows above the curve indicate actuating of the operating panel 12.

The downward displacement movement of the base door 7 starts withtwo-handed actuating of the displacement switch panels 25, 26 or, as thecase may be, of the OPEN switches 25 b or, as the case may be, 26 b, asindicated by the top left vertical arrow. The control circuit 13regulates the drive motor 9 in such a way that the base door 7 will bemoved gently, i.e. with a defined ramp R1, up to its setpoint speed of,in this case, vL=50 mm/s. The ramp R1 is in that case linear. So thedrive motor 9 is not simply turned on.

The displacement movement is as a result also load-independent, inparticular independent of any additional loading of the base door 7 orof any changes in the frictional conditions within the mechanism. Aninitial variable for this can be the rotational speed, measurable by,for example, Hall sensors, of the drive motor 9.

The base door 7 moves constantly downward after reaching the setpointspeed of vL=50 mm/s until approaching the maximum opening PZ determinedby the maximum displacement of the base door 7 specified in its designor by reaching of the work plate 8. It is assumed in that figure thatthe maximum opening PZ specified in the design is reached. In that casethe control circuit 13 will detect said approaching and automaticallybrake the base door 7 gently, i.e. with a defined ramp R2, at PZ. Bothramps R1 and R2 can have other inclinations or shapes. Approaching ofthe base plate can be detected by end switches 33 and/or throughmonitoring of the displacement path.

If one or both of the displacement switches 25 b, 26 b is/are released,as indicated by the top left vertical arrow, the base door 7 will stopabruptly without a ramp, as indicated by the dotted arrow. So althoughmoving starts gently in that mode, it will stop abruptly—except when thefinal position has been reached.

The cooking chamber 3 will not be opened, meaning the base door 7 willnot be displaced from the zero position P0, if an opening-protectionmeans is active, so if, for example, a specific temperature in thecooking chamber, for example 425° C. or 600° F., has been exceeded or achild-protection means has been activated.

FIG. 7 is a graph, not to scale, analogous to FIG. 6 relating to adisplacement of the base door 7 from the closed condition to a storedposition P1=476 mm during automatic displacement operation.

In that case the base door 7 starts moving automatically toward theposition P1 through brief actuating of one of the OPEN switches 25 b or,as the case may be, 26 b, as indicated by the top right vertical arrow.The base door 7 will in that case, too, start being moved gently (rightramp) and braked automatically (left ramp). With that embodiment variantit is possible during automatic operation to select between two fixedsetpoint speeds, namely 75 mm/s (dashed line) and 50 mm/s (unbrokenline), with the slower speed being favorable especially for older users.The slower speed setting is the default in, for example, the conditionas supplied. More than two speed settings or, as the case may be,setpoint speeds can also be provided; flexible setting of the setpointspeed(s) by the user is also conceivable. It is favorably also possibleto change over between at least two speed settings of 50 mm/s and 65mm/s, for example when the appliance is being initialized.

FIG. 8 is a graph, not to scale, relating to a displacement of the basedoor 7 from the maximum open position PZ to the zero position P0,meaning to the closed condition, during manual operation.

The upward displacement movement of the base door 7 starts withtwo-handed actuating of the CLOSE switches 25 a or, as the case may be,26 a, as indicated by the top left vertical arrow. The control circuit13 regulates the drive motor 9 in such a way that the base door 7 willbe moved gently from PZ up to its setpoint speed of vL=50 mm/s, then bemoved constantly at that setpoint speed (to the right).

The control circuit 13 will detect approaching of the zero position P0and gently brake the base door 7 in good time in advance. However,instead of its then continuing down to the zero position P0 directly bymeans of the linear ramp, 4 mm before the zero position P0speed-dependent controlling will be switched over to controlling bymeans of a defined voltage, i.e. through supplying the motor 9 with anappropriate voltage. That will allow maximum force to develop withblocking of the drive motor 9. Said voltage will differ depending on theprior displacement history (additional loading, frictional conditionsetc.). The 4-mm opening extent is detected through travel measuring oradditionally or alternatively by way of the end switches 33. It is alsopossible to dispense with jamming protection in the range from P0 toP0+4 mm.

If, as in FIG. 6, one or both of the displacement switches 25 b, 26 bis/are released, as indicated by the top right vertical arrow, the basedoor 7 will stop abruptly without a ramp, as indicated by the dottedarrow.

FIG. 9 is a graph, not to scale, relating to a displacement of the basedoor 7 from a stored position P1=476 mm to the closed condition P0during automatic displacement operation. In contrast to the manualdisplacement operation shown in FIG. 8, only one of the CLOSE switches25 a, 26 a now needs to be briefly actuated, as indicated by the topvertical arrow. The base door 7, analogous to FIG. 7, will then onlymove in the other direction. When the zero position P0 is approached,then analogously to the situation shown in FIG. 8 for the last 4 mm ofopening the brake ramp will change from a speed-controlled condition toone controlled by load or, as the case may be, closing force.

FIG. 10 is a graph, analogous to FIG. 8, in the case of which jammingnow occurs at a setpoint speed of vL=50 mm/s, as indicated by the topvertical arrow. The speed of the base door 7 will drop when a hand or apot for example becomes jammed between the base door 7 and the housing 1because the object will prevent further displacing. The lifting speed ishere monitored by, for example, evaluating the motor shaft's sensorsignals, with, for example, the time between the measuring signals or,as the case may be, pulses being evaluated. The motor current ismonitored only as a secondary measure, which is a somewhat slowermethod. The force that can be produced by the motor 9 for displacing isin particular limited to prevent accidents due to too tight jamming (seealso FIGS. 12 and 13). Any deviations from the setpoint speed will bedetected by the control circuit 13 based on, for example, a deviation inspeed or change therein over time. The base door will then reverse sothat the object can be removed; an acoustic, for instance, warningsignal may also be fed out. The base door 7 will thereafter only startmoving once a displacement-button panel 25, 26 has been actuated againappropriately.

So that a jamming incident will not be triggered erroneously owing to,for example, changed additional loading or a change in the mechanism'srunning properties, firstly, jamming protection can be activated onlyonce the base door 7 has reached its setpoint speed (the base door 7will stop immediately if a displacement button 25 a, 25 b, 26 a, 26 b isreleased before that) and, secondly, a plurality of sensor signals canbe evaluated, for example averaged.

FIG. 11 shows a jamming incident (top vertical arrow) occurring whilethe base door 7 is being displaced into an open target position P1during automatic operation during which an object becomes jammed betweenthe underside of the base door 7 and the work plate 8. In that casejamming can be detected via two redundant end switches that detect—inparticular uneven—unloading of the base door 7, whereupon the drivemotor 9 will reverse. The maximum permitted force-time profile (seeFIGS. 12 and 13) will therein not be exceeded.

FIG. 12 shows as a first force-time profile FT1 a maximum force F in Nthat can be applied to the base door 7 during a jamming incidentoccurring during displacement in a closing direction (meaning upward),plotted against the expired time t in s.

During a jamming incident at t=0 s the possible closing force is limitedfor 5 s to 100 N, corresponding approximately to 10 kg. That will beexpedient if, for example, the motor 9 is stepped up by the controldevice 13 in order to maintain the setpoint speed. This will ensure inparticular that parts of the body will not be injured. If the base dooris pulled for 5 s with a force of (at most) 100 N, the maximum forcethat can be applied will be further reduced to 25 N, for example for 5seconds. Said force level can thereafter either be maintained or furtherreduced to, for example, 0 N. It must be emphasized that said force-timeprofile FT1 indicates only the maximum force that can be applied andthat the force actually applied will as a rule be less if, for example,the jamming incident is detected by the control device 13 and the basedoor 7 reversed accordingly after t=0.5 s, whereupon the force beingapplied will drop from 100 N to, for instance, 0 N.

The maximum force threshold of 100 N can also apply to otherdisplacement situations.

FIG. 13 shows as a second force-time profile FT2 a maximum force F in Nthat can be applied to the base door 7 during a jamming incidentoccurring during displacement in an opening to the base door 7 during ajamming incident occurring during displacement in an opening direction(meaning downward), plotted against the expired time t in s. The drivemotor 9 can here in a first block of t=[0 s; 0.5 s] be applied to thebase door 7 with a force of up to 400 N, thereafter at t=[0.5 s; 5 s]with a force of 150 N, and thereafter with a force of 25 N.

The time intervals and force thresholds of the force-time profiles FT1,FT2 can of course be accommodated to physical structure and otherboundary conditions.

LIST OF REFERENCES

-   1 Housing-   2 Wall-   3 Cooking chamber-   4 Viewing window-   5 Muffle-   6 Muffle opening-   7 Base door-   8 Work plate-   9 Drive motor-   10 Lifting element-   11 Control element-   12 Operating panel-   13 Control circuit-   14 Display elements-   15 Cooking area-   16 Cooking-hob heating element-   17 Cooking-hob heating element-   18 Panel heating element-   19 Glass ceramic plate-   20 Securing part-   21 Support for items being cooked-   22 Top-heat heating element-   23 Fan-   24 Seal-   25 Displacement switch panel-   25 a Displacement switch, upward-   25 b Displacement switch, downward-   26 Displacement switch panel-   26 a Displacement switch, upward-   26 b Displacement switch, downward-   27 Memory unit-   28 Actuating button-   29 Main switch-   30 Motor shaft-   31 Hall element-   32 Sensing element-   33 End switch-   FT1 First force-time profile-   FT2 Second force-time profile-   P0 Zero position-   P1 Intermediate position-   P2 Intermediate position-   PZ Final position-   R1 Speed ramp-   R2 Speed ramp-   vL Displacement speed of the base door

1-21. (canceled)
 22. An elevated cooking appliance comprising: at leastone muffle defining a cooking chamber, with the at least one mufflehaving a base side and a muffle opening formed on the base side; a basedoor for moving into and out of a covering relationship with the muffleopening; a drive device operatively associated with the base door, withthe base door being movable by the drive device into and out of acovering relationship with the muffle opening; at least one displacementswitch for selectively moving the base door in a selected direction; anda memory unit for storing at least one target position of the base doorwhereby upon storing a target position and actuation of the at least onedisplacement switch, the base door is automatically moved to a nextselected target position present in the relevant displacement direction.23. The elevated cooking appliance as set forth in claim 22 furtherincluding an actuation button; the at least one target position beingstored by actuating the actuation button with the base door at thetarget position.
 24. The elevated cooking appliance as set forth inclaim 23 further including at least one optical and/or acousticsignaling device; the at least one optical and/or acoustic signalingdevice being activated when the actuation button has been actuated and atarget position stored thereby.
 25. The elevated cooking appliance asset forth in claim 22 further including a jamming protection device; thejamming-protection device being activated when a target position hasbeen stored.
 26. The elevated cooking appliance as set forth in claim 22wherein the memory unit includes at least one volatile memory chip forstoring the target position.
 27. The elevated cooking appliance as setforth in claim 22 further including means for gently starting themovement of the base door and gently braking the base door when a targetposition has been stored.
 28. The elevated cooking appliance as setforth in claim 22 whereby in the absence of a stored target position fora displacement direction, the base door can be displaced only byappropriately actuating at least one of the displacement switch panelcontinuously.
 29. The elevated cooking appliance as claimed in claim 28further including a second displacement switch panel whereby in theabsence of a stored target position for a displacement direction, thebase door can be displaced only by actuating both displacement switchpanels continuously and simultaneously.
 30. The elevated cookingappliance as set forth in claim 29 further including a housing; thedisplacement switch panels being attached to the front of the housing.31. The elevated cooking appliance as set forth in claim 29 furtherincluding a housing; the displacement switch panels being attached toopposite sides of the housing.
 32. The elevated cooking appliance as setforth in claim 28, further including means for gently starting themovement of the base door and for abruptly stopping the moving of thebase door in the absence of a stored target position.
 33. The elevatedcooking appliance as set forth in claim 25 further including means fordeactivating the jamming-protection device in the absence of a storedtarget position.
 34. The elevated cooking appliance as set forth inclaim 22 further including a power-failure buffer; means forre-initializing travel measuring of the base door at the zero position,wherein travel measuring of the displacement path is carried outincrementally; and wherein the drive device includes a motor shaft; atleast one sensor for travel measuring of the displacement path of thebase door, with the sensor located on the motor shaft of the drivedevice.
 35. The elevated cooking appliance as set forth in claim 37wherein the sensor is a Hall sensor.
 36. The elevated cooking applianceas set forth in claim 22 further including a main switch; the base doorbeing displaceable with the main switch deactivated.
 37. The elevatedcooking appliance as set forth in claim 22 wherein automaticdisplacement of the base door can be deactivated when the displacementswitch panel has been actuated for longer than a predetermined actuatingtime.
 38. The elevated cooking appliance as set forth in claim 34wherein said predetermined actuating time is 0.4 seconds.
 39. A methodfor operating an elevated cooking appliance having at least one mufflethat delimits a cooking chamber, a base side, a muffle opening on thebase side, a base door and a drive device with the base door beingdisplaceable by the drive device for closing the muffle opening, atleast one displacement switch panel for enabling the displacement of thebase door direction-dependently, and a memory unit, comprising: storingat least one target position of the base door in the memory unit;actuating the at least one displacement switch panel; and automaticallydisplacing the base door to the next target position present in therelevant displacement direction.
 40. The method as set forth in claim 39further including, in the absence of a stored target function for adirection, continuing to displace the base door in the relevantdisplacement direction only while at least one displacement switch panelis being actuated.
 41. The method as set forth in claim 40 furtherincluding displacing the base door in the relevant displacementdirection only while two (2) displacement switch panels are actuatedsimultaneously.